GLUTATHIONE AND RESISTANCE TO CANCER CHEMOTHERAPY

描述：(申请人摘要)双官能团烷基化剂(例如， 马法兰、环磷酰胺、百菌清)和铂类抗肿瘤化合物 (如顺铂、卡铂)被广泛用于治疗人类 恶性肿瘤。这些化合物的抗肿瘤活性是由于它们的 从而使快速分裂细胞的染色体DNA发生交联的能力 抑制肿瘤细胞增殖，诱导肿瘤细胞死亡。这个 这类药物的治疗效果被认为是由于它们的 与谷胱甘肽(g-谷氨酰半胱氨酸甘氨酸)的反应 存在于包括肿瘤细胞在内的所有细胞中。过去发表的研究报告 几年来的研究表明，许多肿瘤的固有或获得性耐药 双官能性烷基化试剂或铂抗肿瘤化合物 与肿瘤中GSH水平升高有关。要扭转这种局面 耐药，携带肿瘤的动物已经注射了丁硫氨酸 亚磺胺(BSO)和谷氨酰半胱氨酸合成酶(GCS)抑制剂 催化谷胱甘肽合成第一步的酶。在这种动物中， GSH利用的持续反应导致GSH耗竭和增加 对烷化剂和铂化合物以及对 放射疗法。丁硫氨酸亚磺胺目前正在接受临床治疗 试验作为马法兰化疗的辅助剂。有效地耗尽 肿瘤GSH要求GSH的合成有效且始终如一 抑制；GSH合成的潜在速率足够高， 即使是GCS抑制的短暂失误也会导致大量的GCS重复 肿瘤GSH与耐药性的恢复。申请者建议开发 通过阐明谷胱甘肽合成抑制药物的改进 GCS的酶学研究以及新型抑制剂的合成和测试。 具体目标如下：(1)人类GCS与其相互作用 将对底物和已知的抑制剂进行表征。(2)新的类似物 将合成与g-GCS亲和力提高的BSO，并进行体外测试 在活体内。(3)新型共价反应性过渡态抑制剂 将合成G-GCS，并在体外和体内进行测试。(4)能力 开发新的抑制剂以提高基于马法兰和顺铂的疗效 人卵巢癌移植瘤的化疗将被描述为 裸鼠。

DESCRIPTION: (Applicant's Abstract) Bifunctional alkylating agents (e.g., melphalan, cyclophosphamide, chlorambucil) and platinum antitumor compounds (e.g. cisplatin, carboplatin) are used to treat a wide range of human malignancies. The antitumor activity of such compounds is due to their ability to crosslink chromosomal DNA of rapidly dividing cells thereby preventing tumor cell proliferation and inducing tumor cell death. The therapeutic efficacy of such agents is believed to be reduced by their reaction with glutathione (g-glutamylcysteinylglycine, GSH) a peptide present in all cells including tumor cells. Studies published over the past several years show that the intrinsic or acquired resistance of many tumors to bifunctional alkylating agents or platinum antitumor compounds is associated with elevated levels of GSH in the tumor. To reverse such resistance, tumor-bearing animals have been administered buthionine sulfoximine (BSO), and inhibitor of gamma-glutamylcysteine synthetase (GCS) the enzyme catalyzing the first step in GSH synthesis. In such animals, the ongoing reactions of GSH utilization cause GSH depletion and increased sensitivity to alkylating agents and platinum compounds as well as to radiation therapy. Buthionine sulfoximine is currently undergoing clinical trial as an adjuvant to melphalan chemotherapy. Effective depletion of tumor GSH requires that GSH synthesis be potently and consistently inhibited; the potential rate of GSH synthesis is sufficiently high that even a brief lapse in GCS inhibition can result in substantial repletion of tumor GSH and restoration of resistance. The applicant proposes to develop improved agents for inhibition of GSH synthesis by elucidating the enzymology of GCS and by synthesizing and testing novel inhibitors. Specific aims are as follows (1) The interaction of human GCS with its substrate and known inhibitors will be characterized. (2) Novel analogs of BSO with improved affinity for g-GCS will be synthesized and tested in vitro and in vivo. (3) Novel covalently reactive transition state inhibitors of g-GCS will be synthesized and tested in vitro and in vivo. (4) The ability of novel inhibitors to increase efficacy of melphalan- and cisplatin-based chemotherapy of human ovarian cancer xenografts will be characterized in nude mice.